Wave signaling system



June 16, 1925. 1,541,780

E. H. ARMSTRONG WAVE SIGNALING SYSTEM Filed June 8, 1922 244% Mfr BMWgum QM Mm ymz, ATTORNEYS Patented June 16, 1925 UNITED STATES EDWIN H.ARMSTRONG, OF YONKERS, NEW Y PATENT OFFICE.

ORKQASSIGNOR, BY MESNE ASSIGN- TION OF PENNSYLVANIA.

WAVE SIGNALING SYSTEM.

, Application filed June 8,

To all whom it may concern:

Be it known that I, EDWIN H. A M- STRONG, residing at 1032 VVarburtonAvenue, Yonkers, in the county of \Vestchestcr, State of New York, haveinvented certain new and useful Improvements in Wave Signaling Systems;and I do hereby declare the following to be a full, clear, and exactdescription of the invention, such as will enable others skilled in theart to which it appertains to make and use the same.

This invention relates to an electric regenerative system for amplifyingvarying electric currents, particularly radio or other high frequencysignaling currents, wherein the varying potential of the current'to beamplified is impressed on the system and the relation between the amountof regeneration and the degree of damping of the system is periodicallyvaried to produce transient free oscillations proportional to theamplitude of the impressed potential and wherein the resulting freeoscillations and the system are continuously maintained in thistransient ordinarily unstable state to obtain super-regenerativeamplification or action as described in my Patent 1,424,065 granted July25, 1922, on a co-pending application, Serial No. 480,568 filed June 27,1921. Y

The invention has for its particular object the provision of a form ofcircuit arrangement capable of producing super-regeneration whereby highamplifications may be obtained without introducing irregularities inoperation resulting in distortion. To this end a regenerative system ofany of the known forms may be used in conjunction with a specific formof oscillating feed-back circuit employing a vacuum tube in which thetuned grid circuit is maintained in the oscillating state by localenergy supplied thru a small condenser connected between the grid andplate of the tube. This condenser may be the sole means for feeding backenergy in the circuit. The feedback oscillating circuit is adapted tosupply an auxiliary frequency to the system which frequency may be lowas compared to the frequency of the current to be amplified, and thecircuit should be so associated with the high frequency regenerativeamplifying system as to continuously and periodically vary the relationbetween the amount of re- 1922. Serial No. 566,681.

generation and the degree of damping of the system, as described in myco-pending applicationmentioned above. This variation is accomplished inaccordance with the present invention by the continuous periodicvariation of the degree of damping, that is, the rate of dissipation ofthe energy of the system, with respect to the amount of regeneration,that is, the regenerative energy supplied to the circuit (the so-callednegative resistance).

The particular form of circuit arrangement illustrated in the drawingsis the preferred embodiment of the invention. It possesses markedadvantages in enabling adjustment of the strength of the auxiliaryfrequency and the amount of regeneration to a point where extremely highamplification may be obtained without introducing irregularities in theoperation of the system resulting in distortion, particularly whenemployed for the reception of radio telephone signals and other signalsof like character.

Referring now to the drawing, the source 1, of the varying current to beamplified is associated with and is adapted to impress the varyingpotential of the current to be amplified, on a regenerative system, .inthis case, a feedback circuit comprising the grid circuit 2, 3 of thevacuum tube 4 and the feed-back coil 5 in the plate circuit of the tube4. There is also included in the plate circuit of the tube 4 a battery 6adapted to supply energy to the system in the well known manner.

Associated with the regenerative system above referred to andeffectively connected across the tuned circuit 2, 3 of the tube 4 is asecond "acuum tube 11. The grid circuit of the tube 11 includes thetuned circuit 7, 8 and the grid circuit of the vacuum tube 4, theoscillating system including the tube 11, and the regenerative systemincluding the tube 4, being associated by a direct connection betweenthe filaments 9, 10 and a variable contact 19 on the inductance 2. Itwill, therefore, be understood that the degree of damping of theregenerative system is varied by the auxiliary frequency produced by thetube 11, which frequency in turn is controlled by the tuning of thecircuit 7, 8. As pointed out above, the circuit 7, 8 is tuned andadjusted to the desired auxiliary frequency at which the relationbetween the amount of regeneration and the degree of damping of theregenerative system is desired tobe continuously and periodically variedto produce super-regenerative amplification. In this case the tube 11,producing the auxiliary frequency serves 'to vary the degree of dampingof the system with respect to the amount of regeneration; the amount ofregeneration being capable of being adjusted to some fixed value in aknown manner, for example, by variation of the amount of couplingbetween the coil 5 and the inductance 2.

The feed-back oscillating circuit including the tube 11, contains thecondenser 12, connected between the grid 18 and the plate 13, and servesas a ready means for con trolling the amount of feed-back and theoscillating condition of the circuit. The oscillating circuit alsoincludes the plate inductance 15 and the small inductance 14, which actsas a choke for incoming signals and which also prevents an alteration ofcapacity produced by the variation of condenser 12 from effecting thetuning of the circuit 2, 3.

The vacuum tube 4 acts as a generator delivering currents of a frequencydetermined by the tuning of the circuit 2-3. Energy, for maintainingthis oscillation, is supplied inductively by the coil 5 acting upon thecoil 2 in the usual way. The tube 11 generates currents, the frequencyof which is determined by the tuning of the circuit -7--8. The platecircuit of this tube includes the inductance 15 and the telephone 16 aswell as the battery 1.7 Fluctuations upon the grid 18 causecorresponding fluctuations in the current in the plate circuit with aconsequent change in voltage at the junction of the inductance 15 andthe condenser 12. The changes in voltage upon the condenser 12 thusserves to impress energy upon the oscillating circuit 7-8 and, in thisway, maintain the tube 11 in oscillation. The impedance of theconnection 1214 is regulated by adjusting the condenser 12. The quantityof energy fed to the circuit 7-8 is thus adjusted.

Each time that the grid 18 becomes positive (because of the alternatingpotential of the point in the circuit 78 to which the grid is connected)a conductive connection is established from the tap 19 through thecondenser 8 and the space-current path 18 10 to the other side of thecircuit 23. This connection is, in efiect, a shunt between the grid andfilament in tube 4. It thus affords an outlet for the energy of theoscillations in the circuit 23 and so increases the damping of saidoscillations.

Each time the grid 18 becomes negative the shunt ceases to be conductingand the oscillations in circuit 23 build up to a maxi- At the curvedpart of the characteristic, the

tube hasa detector action.

The oscillations of the circuit 23 cause changes in the negativepotential of the grid 18 and the detector action of the tube 11 causescorresponding pulsations in the plate circuit including the telephone16. During any one group of pulsations, a charge is built up on thecondenser 20. During the space between two groups, the charge passesthrough the telephone 16. Group frequency being above audio frequency,these discharges through the telephone do not produce an audible sound.The degree to which the condenser 20 becomes charged depends on theamplitude of the pulsations. it

This amplitude varies at audio frequency. The discharges through thetelephone, therefore, are modulated at audio frequency and thismodulation is perceived as an audible signal.

It is to be understood that the present in vention is adapted to receiveradio signals, including radio telephone signals, when associated withan antenna, loop or other energy collecting device and to receive wiredwireless signals (so-called wire carrier current transmission) whenassociated with the conductors of such signals. It should also beunderstood that modifications may he made in the specific circuitconnections above described without departing from the spirit and scopeof the invention.

I claim:

1. An electric regenerative system adapted to produce super-regencrativeaction, including a feed-back circuit having a certain degree of dampingand means for periodically varying the relation between the amount offeed-back and the degree of damping of the system comprising a genera--tor of electrical oscillations adapted to supply an auxiliary frequencyto the regenerative system and a capacity in said generator forcontrolling and maintaining the oscillations in said oscillating system.

2. An electric regenerative system adapted to produce super-regenerativeaction, including a feed-back circuit having a certain degree of dampingand means for periodically varying the relation between the amount offeed-back and the degree of damping of the system comprising a feed backoscillating circuit having grid and plate elements and a variablecapacity connected between said elements, said capacity being adapted tocontrol and maintain the oscillations in said oscillating system.

3. Apparatus for amplifying varying electric currents comprising afeed-back circuit including a vacuum tube having a certain degree ofdamping and means for periodically altering the relation bevveen theamount of feed-back action and the degree of damping of the systemwhereby super regenerative action is obtained, said means comprising afeed-back oscillating circuit including a vacuum tube having grid andplate elements and a variable capacity connecting said elements, saidcapacity being adapted to control and maintain the oscillations in saidoscillating system.

4. An electric regenerative system adapted to produce super-regenerativeaction comprising a feed-back circuit having a certain degree of-dampingand including a vacuum tube having grid, filament and plate elements, atuned circuit connected between said grid and filament elements and afeedback coil connected betweensaid plate and filament elements andassociated with said tuned circuit, a second feed-back circuit

